proportional valve: how important to have working one?

[Bernard Littau]

> This is a dealer-only part, I'm told, and is quite expensive even
> with List
> discounts.

> >Did anybody feel a difference in praking after replacing bad proportional
> >valve?
> >

I replaced mine with a used one fresh off a front-end wreck 18 months ago.
I remember it was expensive for a used part.

My original had been left connected when the suspension was dropped, so the
spring was over-stretched and the arm was mangled.  Near as I could tell it
was always allowing the minimum brake effect.

The replacement appears to be working correctly, but I have never noticed a
difference.  I've certainly never locked up the rears without the fronts
locking first with either proportioning valve.

I did buy a fitting that can be used to "bypass" the valve, which would
present the maximum brake effect to the rears, but I never installed it.
One of the reasons I didn't try it is because it appeared to me the
proportioning valve never lets 100% brake effect through, which the fitting
would do.  I guess I should try it some time and report back.

Best,

Bernard Littau
Woodinville, WA
'88 5ktq